Breaches in the pial basement membrane causes ectopia of granule cell precursors during development.
Newborn forebrain sections were double stained with antibodies against laminin-1 (red fluorescence) and Prox1(green fluorescence) and counterstained with DAPI (blue fluorescence). (A) Wildtype. The pial basement membrane of the dentate gyrus (arrows) and the midbrain (arrowheads) was clearly observed. Prox1-positive granule cells in the lower blade were separated from the pial basement membrane by at least 50 μm. (B) POMGnT1 knockout. The pial basement membrane of the dentate gyrus in this section was broken into pieces while the pial basement membrane of the midbrain appeared intact. Ectopia of Prox1-positive granule cells was apparent (square). (C) POMT2f/f;Emx1-Cre(+). The pial basement membrane of the dentate gyrus was absent in this section while the pial basement membrane of the midbrain was intact. Ectopic Prox1-positive granule cells were clearly observed (square). (D) Largemyd mice. In this section, the pial basement membrane of the dentate gyrus was absent and the pial basement membrane of the midbrain was also disrupted. Where indicated by asterisks, there was no intact pial basement membrane. Ectopia of Prox1-positive neurons was clearly observed. Scale bar in D: 50 μm.